Valve with fail-safe device

ABSTRACT

A power operated valve for controlling fluid flow is provided with a fail-safe device responsive to failure of the power supply to the valve to shut-off fluid flow. A valve member is coupled to linear actuator for movement towards and away from a closed position for controlling fluid flow through the valve. The linear actuator is held in a control position by the fail-safe device for normal operation of the valve with the power supply on. The fail-safe device responds to failure of the power supply to release the linear actuator. When the linear actuator is released, energy stored n a spring while the linear actuator was held in the control position is released and biases the linear actuator away from the control position causing the valve member to move to the closed position to shut-off fluid flow.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of U.S. patent application Ser.No. 14/878,788, filed Oct. 8, 2015, which is a Continuation of U.S.patent application Ser. No. 13/799,908, filed Mar. 13, 2013 (now U.S.Pat. No. 9,182,047). The entire disclosures of U.S. patent applicationSer. Nos. 14/878,788 and 13/799,908 are incorporated herein byreference.

BACKGROUND

The present application relates to valves for controlling flow of afluid. More especially, the application relates to a fail safe mechanismfor power operated valves. The concepts disclosed herein haveparticular, but not exclusive, application to valves for controllingflow of one or more fluids. The concepts disclosed herein may haveapplication to plumbing fittings and fixtures and water supply systemsand installations for washing, showering, bathing and the like thatemploy such plumbing fittings and fixtures.

Power operated valves are known in which a valve member is moveablerelative to a valve seat between open and closed positions by means of alinear actuator for controlling fluid flow. Such valves can be left inan open position in the event of a power supply failure allowing fluidflow to continue in an uncontrolled manner until the power supply isrestored. The present application is intended to address this problem.

SUMMARY

An exemplary embodiment relates to a valve for controlling fluid flowand a fail-safe device responsive to failure of a power supply to thevalve, the valve including a valve member coupled to an actuator formovement towards and away from a closed position for controlling fluidflow through the valve, wherein the actuator is held in a controlposition by the fail-safe device for normal operation of the valve withthe power supply on and is released in response to failure of the powersupply for movement of the actuator and valve member towards the closedposition.

Another exemplary embodiment relates to a method of operating a valvefor controlling fluid flow, the method including coupling a valve memberto an actuator for movement towards and away from a closed position forcontrolling fluid flow through the valve, holding the actuator in acontrol position for normal operation of the valve, and releasing theactuator in response to failure of a power supply to the valve formovement of the actuator and valve member towards the closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a valve and fail-safe device according toa first embodiment with the valve in a closed position;

FIG. 2 is a sectional view of a valve and fail-safe device shown in FIG.1 with the valve in an open position during normal operation with thepower on;

FIG. 3 is a sectional view of the valve and fail-safe device shown inFIGS. 1 and 2 with the valve in a closed position during fail-safeoperation with the power off;

FIG. 4 is a sectional view of a valve and fail-safe device according toa second embodiment with the valve in an open position during normaloperation with the power on;

FIG. 5 is a sectional view of the valve and fail-safe device shown inFIG. 4 with the valve in a closed position during fail-safe operationwith the power off;

FIG. 6 shows the fail-safe device of FIGS. 4 and 5 in a closed state fornormal operation of the valve with the power on;

FIG. 7 shows the fail-safe device of FIG. 6 in an open state forfail-safe operation of the valve with the power off:

FIG. 8 shows a modification to the fail safe device shown in FIGS. 6 and7 in a closed state for normal operation of the valve with the power on;

FIG. 9 shows the fail-safe device of FIG. 8 in an open state forfail-safe operation of the valve with the power off;

FIG. 10 is a sectional view of a valve and fail-device according to athird embodiment with the valve in a closed position during fail-safeoperation with the power off;

FIG. 11 is a sectional view of a valve and fail-safe device according toa fourth embodiment with the valve in a closed position;

FIG. 12 is a sectional view of a valve and fail-safe device shown inFIG. 11 with the valve in an open position during normal operation withthe power on; and

FIG. 13 is a sectional view of the valve and fail-safe device shown inFIGS. 11 and 12 with the valve in a closed position during fail-safeoperation with the power off.

DETAILED DESCRIPTION

An exemplary embodiment relates to a valve for controlling fluid flowand a fail-safe device responsive to failure of a power supply to thevalve. The valve may have a valve member coupled to an actuator formovement towards and away from a closed position for controlling fluidflow through the valve. The actuator may be held in a control positionby the fail-safe device for normal operation of the valve with the powersupply on. The actuator may be released in response to failure of thepower supply for movement of the actuator and valve member towards theclosed position.

The actuator may be biased away from the control position. The biasingmay be provided by a spring. The spring may be in an energized statewhen the actuator is held in the control position. Energy stored in thespring in the energized state may be employed when the actuator isreleased to move the actuator and valve member towards the closedposition. The valve member may be moved to a safe position in responseto fail-safe operation. The valve member may be moved to the closedposition to shut-off fluid flow. Alternatively, the valve member may bemoved to a position in which some fluid flow is permitted.

The actuator may be held in the control position by a magnetic coupling.The fail-safe device may include a latch unit configured to create amagnetic attraction force to hold the actuator in the control position.The latch unit may include an electromagnet. The actuator may be held inthe control position by the electromagnet when the power supply is onand is released when the power supply is interrupted. The magneticattraction force exceeds the biasing force to retain the actuator in thecontrol position until the actuator is released. The magnetic attractionforce may be slightly higher than the biasing force in the controlposition.

The actuator may be held in the control position by a mechanicalcoupling. The fail-safe device may include a latch unit configured toengage the actuator to hold the actuator in the control position. Thelatch unit may include a catch. The actuator may be held in the controlposition by the catch when the power supply is on and is released whenthe power supply is interrupted. The biasing force is stored in thecontrol position of the actuator and is released when the actuator isreleased.

The valve member may remain in the safe position when power to the valveis restored following fail-safe operation until the actuator is re-setin the control position. The actuator may be a linear actuator, forexample a stepper motor. The actuator may be coupled to the valve memberby a coupling unit for converting rotational movement of the actuatorinto linear movement of the valve member towards and away from theclosed position. The actuator may be operable to move relative to thevalve member for re-setting the actuator in the control position.

Another exemplary embodiment relates to a method of operating a valvefor controlling fluid flow. The method may include coupling a valvemember to an actuator for movement towards and away from a closedposition for controlling fluid flow through the valve. The method mayfurther include holding the actuator in a control position for normaloperation of the valve. The method may further include releasing theactuator in response to failure of a power supply to the valve formovement of the actuator and valve member towards the closed position.

Other features, benefits and advantages of the valve described hereinwill be apparent from the description hereinafter of exemplaryembodiments thereof and of the application of the valve to plumbingfixtures and fittings and water supply systems and installationsemploying such plumbing fixtures and fittings. Such description isprovided for the purpose of demonstrating the diverse ways in which thevalve can be configured and used and is not intended to be limiting onthe scope of the disclosure.

There now follows by way of example only a detailed description ofvarious exemplary embodiments disclosed in the present application, withreference to the accompanying drawings.

Referring first to FIGS. 1 to 3 of the accompanying drawings a valve 1and fail-safe device 3 according to a first embodiment of the inventionis shown. The valve 1 is described in the aforementioned United KingdomPatent Application No. 1211101.9, filed Jun. 22, 2012, the entiredisclosure of which is incorporated herein by reference. In thedescription that follows the valve 1 is described only insofar asnecessary for an understanding of the operation of the fail-safe device3 and the reader is directed to the disclosure of United Kingdom PatentApplication No. 1211101.9, filed Jun. 22, 2012 for a more detaileddescription of the valve 1 and applications thereof.

The valve 1 includes a body 4 of metal, for example brass, althoughother materials may be used. The body 4 houses a first flow controlvalve 5 for a first fluid and a second flow control valve 7 for a secondfluid. The first and second fluids may be water having differenttemperatures (nominally hot and cold water). The valve 1 provides waterhaving a desired temperature for use. The valve 1 may provide cold wateronly, hot water only or a mixture of hot and cold water. The valve 1 maybe incorporated in a water supply system or installation having one ormore outlets for washing, showering, bathing or the like. Each outletmay include a faucet incorporating the valve 1. Alternatively, the valve1 may be incorporated in a fitting supplying more than one outlet. Forexample multiple shower heads may be supplied with water from one valve1. Other applications and uses of the valve 1 will be apparent to thoseskilled in the art from the description of the invention provided hereinand the invention extends to and includes all modifications and changeswithin the spirit and scope of the disclosure.

The flow control valves 5 and 7 are similar and there follows adescription of the construction and operation of the first flow controlvalve 5. The same reference numerals have been used but with anadditional apostrophe to identify similar features of the second flowcontrol valve 7 such that the construction and operation of the secondflow control valve 7 will be apparent and understood from thedescription of the first flow control valve 5.

The first flow control valve 5 includes an inlet chamber 9 connected toan inlet (not shown) for a first fluid and controls flow of the firstfluid from the inlet chamber 9 to a mixing chamber 11. The mixingchamber 11 provides a volume in which the first and second fluids canmix and directs the mixed fluid to an outlet 12.

The first flow control valve 5 includes first and second valve members13, 15 fixedly mounted on a spool 17 such that they are held apredetermined distance apart. The first valve member 13 is adapted toco-operate with a first valve outlet 19 at one end of the inlet chamber9 and the second valve member 15 is adapted to co-operate with a secondvalve outlet 21 at the other end of the inlet chamber 9. The first andsecond valve outlets 19, 21 are axially aligned and open to the mixingchamber 11. The valve members 13, 15 may be made of rubber.

A first end of the spool 17 is slidably received within a blind guidebore 23 formed in the valve body 4. A second, opposed end of the spool17 is connected to a shaft 25 of an actuator 27 by a coupling unit 29for converting rotational movement of the shaft 25 into linear movementof the spool 17. The actuator 27 comprises an electrically-poweredmotor, for example a stepper motor. Suitable stepper motors may of atype supplied by Haydon Kerk. Any actuator 27 for controlling linearmovement of the spool 17 may be employed including, but not limited to,linear actuators.

The coupling unit 29 includes a tube 31 of corrosion resistant material,for example stainless steel, a drive member 33 of plastic material, andan anti-rotation member 35 also of plastics material. The tube 31 issecured at one end, for example by crimping, to the second end of thespool 17. The other end of the tube 31 is secured to the drive member33. An annular seal member 37 of U-section provides a fluid tight sealfor passage of the tube 31 through an opening 39 at one end of a bore 41in the body 4 of the valve 1 to prevent leakage of water from the mixingchamber 11.

The drive member 33 is mounted on the shaft 25 of the actuator 27 andhas an internal screw threaded portion 43 co-operable with an externalscrew threaded portion 45 of the shaft 25. The anti-rotation member 35is mounted on the actuator 27 and the drive member 33 is located in anaxial bore 47 of the anti-rotation member 35. The drive member 33 andbore 47 are configured to permit axial sliding movement of the drivemember 33 relative to the anti-rotation member 35 while preventingrotational movement of the drive member 33 relative to the anti-rotationmember 35. For example the bore 47 may be of cruciform shape and thedrive member 33 provided with ribs that co-operate with the cruciformshape to prevent rotational movement of the drive member 33 whileallowing axial movement. This arrangement converts rotational movementof the shaft 25 into linear movement of the drive member 35 that istransmitted to the spool 17 of the flow control valve 5 via the tube 31for moving the valve members 13, 15 axially relative to the valveoutlets between open and closed positions for controlling flow of fluidfrom the inlet chamber 9 to the mixing chamber 11. Any other arrangementfor converting rotational movement of the shaft 25 into axial movementof the spool 17 may be employed.

The valve 1 may include a controller (not shown) which provides controlsignals to the actuators 27, 27′ of the first and second flow controlvalves 5, 7. The controller may also include a temperature sensor and/orflow rate sensor to measure the temperature and/or flow rate of thewater at the fluid outlet 12 of the valve 1 or at any other relevantpoint in the fluid flow path within the valve 1 or external thereto. Thesignals from the sensor(s) may be used to control the actuator 27, 27′of each flow control valve 5, 7 to control the temperature and/or flowrate of the water leaving the outlet 12. For example the signals may beused to maintain a desired temperature and/or flow rate or to providefeedback to the controller so that the water leaving the outlet 12corresponds to desired settings despite changes in the water pressureand temperature at the first fluid inlet and/or second fluid inlet. Thecontroller may include an interface to receive settings input by a user.Wired or wireless communication may be provided between the controller,sensor(s) and interface.

The fail-safe device 3 is arranged to shut-off fluid flow in the eventof a power supply failure occurring while one or both flow controlvalves 5, 7 is in an open position. The fail-safe device 3 includes alatch unit 49 for the actuator 27 of the first flow control valve 5 anda latch unit 51 for the actuator 27′ of the second flow control valve 7.The latch units 49, 51 are arranged to hold the actuators 27, 27′ in acontrol position for normal operation of the valve 1 shown in FIGS. 1and 2 when the power supply to drive the actuators 27, 27′ is on and torelease the actuators 27, 27′ for movement to close the flow controlvalves 5, 7 during fail-safe operation of the valve 1 shown in FIG. 3 ifthe power supply to drive the actuators 27, 27′ is interrupted when oneor both of the flow control valves 5, 7 is open.

The latch units 49, 51 are similar and there follows a description ofthe construction and operation of the latch unit 49 for the first flowcontrol valve 5. The same reference numerals have been used but with anadditional apostrophe to identify similar features of the latch unit 51for the second flow control valve 7 such that the construction andoperation of the latch unit 51 for the second flow control valve 7 willbe apparent and understood from the description of the latch unit 49 forfirst flow control valve 5.

The latch unit 49 includes an armature 53 of magnetic material such assteel that is fixed to the actuator 27 of the first flow control valve 5and an electromagnet 55. The electromagnet 55 is connected to the powersupply for the actuator 27 and the magnetic attraction force between thearmature 53 and the electromagnet 55 is chosen to couple the armature 53to the electromagnet 55 to hold the actuator 27 in the control positionagainst the biasing of a compression spring 57 acting between thearmature 53 and the electromagnet 55 when the power supply to drive theactuator 27 is on.

In the control position, the actuator 27 is operable to move the spool17 between the closed position of the first flow control valve 5 shownin FIG. 1 and the full open position of the first flow control valve 5shown in FIG. 2 for controlling flow of the first fluid from the inletchamber 9 to the mixing chamber 11. The actuator 27 can move the spool17 to position the first flow control valve 5 at any intermediateposition between the closed and full open positions for varying the flowof the first fluid. Flow of the second fluid can be varied in similarmanner such that the relative proportions of the first and second fluidsadmitted to the mixing chamber 11 can be adjusted to provide mixed fluidat the outlet 12 which in the case of the first and second fluids beingwater having different temperatures can produce mixed water having anydesired intermediate temperature for the intended use such as washing,showering or bathing.

In the event of a power failure occurring when the first flow controlvalve 5 is in an open position, such as the full open position shown inFIG. 2, the magnetic attraction force between the armature 53 and theelectromagnet 55 is lost and the energy stored in the spring 57 isreleased creating a biasing force acting on the armature 53 to move theactuator 27 away from the control position and thus move the spool 17 toclose the first flow control valve 5 as shown in FIG. 3. The second flowcontrol valve 7 is closed in similar manner if the power is interruptedwhen this valve 7 is in an open position.

If the power is re-instated after fail-safe operation of the valve 1,the magnetic attraction force between the electromagnets 55, 55′ andarmatures 53, 53′ of the actuators 27, 27′ is insufficient to overcomethe biasing force of the springs 57, 57′ acting on the actuators 27, 27′and the flow control valves 5, 7 remain closed until the valve 1 isre-set.

In order to re-set the valve 1 following a power failure/interruption,the actuators 27, 27′ are operated to rotate the shafts 25, 25′ in adirection to return the actuators 27, 27′ to the control positionwithout moving the spools 17, 17′ so that the flow control valves 5, 7remain closed. The actuators 27, 27′ are guided for movement to and fromthe control position by engagement of the anti-rotation members 35, 35′in the bores 41, 41′ in the body 4. The latch units 49, 51 and actuators27, 27′ are located within a housing 59 connected to the body 4 of thevalve 1.

Once the actuators 27, 27′ have returned to the control position in FIG.1 with the flow control valves 5, 7 closed, the actuators 27, 27′ canagain be operated to control movement of the spools 17, 17′ as describedpreviously for controlling flow of the first and second fluids duringnormal operation of the valve 1.

As will be understood, the above-described fail-safe operation occurswhenever there is a power failure/interruption with one or both flowcontrol valves 5, 7 in an open position. If the flow control valves 5, 7are returned to the closed position shown in FIG. 1 during normaloperation and the power fails or is interrupted in this position, theactuators 27, 27′ remain in the control position even though themagnetic attraction force between the electromagnets 55, 55′ and thearmatures 53, 53′ has been lost because the spools 17, 17′ are seated atthe end of the blind bores 23, 23′ in the valve body 4. As a result, thearmatures 53, 53′ are re-coupled to the electromagnets 55, 55′ whenpower is restored allowing normal operation of the valve 1.

In a modification (not shown), the electromagnets 55, 55′ may bereplaced by a single electromagnet to which both armatures 53, 53′ maybe coupled for holding the actuators 27, 27′ in the control position. Inanother modification (not shown), the compression springs 57 may bereplaced by tension springs arranged so that, when the actuators 27, 27′are released, the actuators 27, 27′ and spools 17, 17′ are moved toclose the valve 1 by the energy stored in the springs when the actuators27, 27′ are held in the control position.

Referring now to FIGS. 4 to 7, an alternative fail-safe device 3 isshown in which the magnetic coupling provided by the latch units 49, 51to hold the actuators 27, 27′ in the control position against thebiasing of the springs 57, 57′ for normal operation of the valve 1 isreplaced by a mechanical coupling. Like reference numerals are used toindicate parts of the valve 1 corresponding to the previous embodiment.

In this embodiment, the actuators 27, 27′ have axial extensions 61, 61′that project through openings in the housing 59 and are provided with anannular groove 63, 63′.

The fail-safe device 3 includes a latch unit 65 for both actuators 27,27′. The latch unit 65 includes a catch plate 67 mounted for rotationabout an axis intermediate the ends. The catch plate 67 engages thegrooves 63, 63′ on opposite sides of the rotational axis to hold theactuators 27, 27′ in the control position against the biasing ofcompression springs 57, 57′ that surround the extensions 61, 61′ and actbetween the housing 59 and the actuators 27, 27′.

The catch plate 67 is biased by a spring 69 in a direction to disengagethe grooves 63, 63′ and is retained in the engaged position by anactuator 71 responsive to failure/interruption of the power supply tothe actuators 27, 27′. In this embodiment, the actuator 71 is providedby a shape memory alloy (SMA) wire loop 73 that extends between thecatch plate 67 and the housing 59.

The SMA wire loop 73 is connected to the power supply to the actuators27, 27′ and contracts when the power is on to oppose the biasing of thespring 69 and maintain the engagement between the catch plate 67 and thegrooves 63, 63′ in the axial extensions 61, 61′ of the actuators 27, 27′to hold the actuators 27, 27′ in the control position for normaloperation of the valve 1 as described previously for the embodiment ofFIGS. 1 to 3.

In the event of failure or interruption of the power supply with one orboth flow control valves 5, 7 in an open position, the SMA wire loop 73extends allowing the catch plate 67 to rotate under the biasing of thespring 69 to disengage the grooves 63, 63′ in the axial extensions 61,61′ of the actuators 27, 27′ thereby releasing the actuators 27, 27′ tomove under the biasing of springs 57, 57′ to close the flow controlvalves 5, 7 as described previously for the embodiment of FIGS. 1 to 3.

When re-setting the valve 1 following fail-safe operation to shut-offflow, the shafts 25, 25′ of the actuators 27, 27′ are rotated in adirection to return the actuators 27, 27′ to the control positionwithout opening the flow control valves 5, 7. This may be done beforepower is re-instated to the latch unit 65 to allow the catch plate 67 tore-engage the grooves 61, 61′ when power is restored and the SMA wireloop 73 contracts to rotate the catch plate 67 against the biasing ofthe spring 69. Alternatively, end faces of the axial extensions 61, 61′may be chamfered to co-operate with and displace the catch plate 67sufficiently to allow the catch plate 67 to re-engage the grooves 63,63′.

Referring now to FIGS. 8 and 9, a modification to the fail-safe device 3of FIGS. 4 to 7 is shown in which a solenoid actuator 75 is provided inplace of the SMA wire loop 73. In this embodiment, the solenoid actuator75 is connected to the power supply to the actuators 27, 27′ andmaintains the engagement of the catch plate 67 with the grooves 63, 63′in the axial extensions of the actuators 27, 27′ when the power is on.In the event of failure or interruption of the power supply, thesolenoid actuator 75 no longer opposes the biasing of the spring 69 andthe catch plate 67 is able to rotate to disengage the grooves 63, 63′and allow the actuators 27, 27′ to move under the biasing of the springs57, 57′ to close the flow control valves 5, 7 as described previouslyfor the embodiment of FIGS. 1 to 3.

In other respects the operation of this modified embodiment is similarto the embodiment of FIGS. 4 to 7 and will be understood from thedescription of FIGS. 4 to 7. Like reference numerals are used toindicate similar parts.

Referring now to FIG. 10, there is shown an embodiment having a singleflow control valve and fail-safe device suitable for applications inwhich it is desirable to control fluid flow. One such application is inan instantaneous water heater of the type commonly used in electricshowers to provide a source of hot water on demand.

FIG. 10 shows the flow control valve 5 and fail safe device 3 from theembodiment of FIGS. 1 to 3 arranged to control flow of a water supply,typically cold water, to a heat exchanger tank (not shown) of aninstantaneous water heater. The control valve 5 has an inlet 76connected to the water supply and an outlet 77 connected to the heatexchanger tank. The inlet 76 opens to the inlet chamber 9 of the flowcontrol valve 5 and the valve outlets 19, 21 open to an outlet chamber79 leading to the outlet 77 through one or more ports 81.

In this type of water heater, the incoming supply of water is heated asit flows through the heat exchanger tank by one or more electric heatingelements. The outlet water temperature from the heat exchanger tank isdependent on the flow rate of the water and the power input to theheater tank. The power input can often be selected by varying the numberand power rating of the heating elements such that, for a given powerinput, the outlet water temperature can be controlled by varying theflow rate.

In this application, if the power supply to the heat exchanger tankfails or is interrupted while the flow control valve 5 is open, the failsafe device 3 is operable to close the valve 5 and shut-off the flow.FIG. 10 shows the flow control valve 5 in the closed position followingfail-safe operation. A time delay may be provided before shutting-offthe flow to allow the heat exchanger tank to be flushed with cold waterto reduce the temperature of the heating elements and prevent any waterremaining in the heat exchanger tank being heated to an elevatedtemperature which may give rise a risk of scalding if the power isrestored and the water heater turned on again soon after fail-safeoperation.

In other respects the construction and operation of the flow controlvalve 5 and the fail-safe device 3 will be understood from thedescription of FIGS. 1 to 3 and like reference numerals are used toindicate similar parts. It will be understood that the flow controlvalve could be replaced by any of the flow control valves shown in FIGS.4 to 9.

Another application where a single flow control valve and fail-safedevice might be provided is to control the flow of water from a mixingvalve. Other applications will be apparent to those skilled in the art.

In the above-described embodiments the or each flow control valve 5, 7is of the type disclosed in United Kingdom Patent Application No.1211101.9, filed Jun. 22, 2012, in which the valve spool 17 is providedwith two valve members 13, 15 for controlling fluid flow through thevalve 1. It will be understood, however, that this is not essential andthat the concepts described herein have wider application to providefail-safe operation of any valve having at least one valve membermovable towards and away from a closed position by means of an actuatorfor controlling flow through the valve.

Referring now to FIGS. 11 to 13, a modification of the valve shown inFIGS. 1 to 3 is shown in which like reference numerals are used toindicate corresponding parts. In this modification, the inlet chambers9, 9′ of the flow control valves 5, 7 open to the mixing chamber 11through a single valve outlet 19, 19′ and the valve spools 17, 17′ areprovided with a single valve member 13, 13′ for controlling flow throughthe valve outlet 19, 19′. In other respects the construction andoperation of the valve 1 and fail-safe device 3 is similar to and willbe understood from the description of FIGS. 1 to 3. A similarmodification may be made to the valve shown in FIG. 10 in which a singleflow control valve is provided.

The fail-safe device 3 shown in FIGS. 11 to 13 employs latch units 49,51 that provide a magnetic coupling to hold the actuators 27, 27′ in thecontrol position. It will be understood however that the latch units 49,51 may be replaced by any of the latch units described herein such asthe latch units shown in FIGS. 4 to 9 that provide a mechanical couplingto hold the actuators 27, 27′ in the control position.

By employing movement of the actuator to close the valve duringfail-safe operation, no components of the fail-safe device are presentin the fluid flow path. In particular, the spring biasing the actuatoris located outside the flow path and is therefore dry and does notprovide a surface area for microbial growth within the fluid flow path.In addition, where a magnetic coupling is employed to hold the actuatorin the control position, the electromagnetic element is stationaryenabling easier connection to the power supply.

Although the exemplary embodiments describe arrangements in which one ormore flow control valves of the type described in United Kingdom PatentApplication No. 1211101.9, filed Jun. 22, 2012 is/are provided with afail-safe device, it will be understood that the fail-safe devicesdescribed herein have wider application and could be employed with anyelectrically powered valve to shut-off flow in the event of failure orinterruption of the power supply to the valve. Moreover, while it maygenerally be desirable to shut-off the flow completely in the event offailure or interruption of the power supply to the valve to preventwaste from uncontrolled flow of fluid (water) through the valve, theremay be applications where it may be desirable to allow some flow offluid (water) to continue. Thus, it may be that the fail-safe device isarranged to control flow to provide a pre-determined flow rather than toshut-off the flow completely. Such pre-determined flow might be requiredin some applications for safety reasons.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” etc.) are merely used to describe the orientation ofvarious elements in the FIGURES. It should be noted that the orientationof various elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

It is important to note that the construction and arrangement of thevalves and related assemblies as shown in the various exemplaryembodiments is illustrative only. Although only a few embodiments havebeen described in detail in this disclosure, those skilled in the artwho review this disclosure will readily appreciate that manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Forexample, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments.

Other substitutions, modifications, changes and omissions may also bemade in the design, operating conditions and arrangement of the variousexemplary embodiments without departing from the scope of the inventionsdescribed herein. Other modifications that can be made will be apparentto those skilled in the art and the invention extends to and includesall such modifications. Any of the features described herein may beemployed separately or in combination with any other feature and theinvention extends to and includes any such feature or combination offeatures whether or not described herein.

What is claimed is:
 1. A valve for controlling fluid flow and afail-safe device responsive to failure of a power supply to the valve,the valve including a valve member coupled to an actuator for movementtowards and away from a closed position for controlling fluid flowthrough the valve, wherein the actuator is held in a control position bythe fail-safe device for normal operation of the valve with the powersupply on and is released in response to failure of the power supply formovement of the actuator and valve member towards the closed position.